A fuel injection pump device for pumping fuel into the fuel injection nozzle of a Diesel engine has been hitherto composed so that the control of a fuel injection quantity is carried out by turning a plunger for pressurizing the fuel in the pump, and composed so that the control of a fuel injection beginning time is carried out by changing the rotating phase of a cam shaft for driving said plunger, which is driven by the engine, with respect to the crank angular phase of the engine by use of a centrifugal auto-timer provided on the cam shaft. In the case where the injection timing is controlled, however, the inertia mass of the cam shaft is relatively larger and the pump driving torque transmitted from the cam shaft to the plunger is large, and such a conventional fuel injection pump device is therefore disadvantageous: a large-sized timer must be used as an inevitable consequence, the cost is accordingly increased and the whole of the pump is made large-scaled.
The conventional pump device shown in FIG. 1 has the following defects. The reference numeral 01 represents a housing, in which a barrel 02 is arranged in its upper part and a cam shaft 04 is arranged in a cam shaft case 03 in its lower part, and the head 06 of a plunger 05 is inserted and slidably arranged in said barrel 02.
A spring shoe 07 is mounted on the center of said plunger 05 and presses down the plunger 05 by virtue of a spring 08 placed between the plunger 05 and the pump housing 01.
Said plunger 05 has an oil port 010 provided therein so as to communicate the head 06 and its lower body portion 09 with each other, and a control sleeve 011 which is turnable and slidable up and down is mounted on the lower body portion 09 and arranged so as to open or shut said oil port 010.
Said control sleeve 011 has an upper lead 012 and an lower lead 013 formed thereon. The sleeve is turned by the movement of an injection quantity control rod 020 in the normal direction to FIG. 1, thereby to control the fuel injection quantity, and the sleeve is slided vertically by way of an eccentric pin 015 by an injection timing control rod 014, thereby to control the fuel injection timing.
In the aforementioned composition in which fuel fed from a fuel source (not shown) such as a feed pump is supplied to a fuel chamber 016 formed in the housing 01 and remains there, however, there is a need of providing a spill-way for the fuel in order to actuate a tappet 017 provided beneath the plunger 05, and a spill port 018 is therefore formed in the said tappet 017, through which spill port 018 a part of the fuel is supplied to the cam shaft case 03.
Said housing 01 is accordingly filled with the fuel and the lubrication of said tappet 017, cam shaft 04 and the likes will be carried out by the fuel itself. Perhaps, seizure is frequently caused to happen because the surface pressure in each lubricating part is too high.
Since the conventional pump device mentioned above is composed so that all of the cam shaft 04, the tappet 017 driven by the cam shaft, the plunger 05 and the spring shoe 07 are sliding in the fuel and the resistance of the fuel becomes therefore larger, it has disadvantages such as a difficult revolution of the engine at a high speed and an excess of heat generated by this resistance.